Circuit simulation is used in integrated circuit design to predict how a circuit behaves prior to the circuit being physically implemented, e.g., fabricated. Circuit simulators, such as SPICE, rely on mathematical compact models of circuit elements to perform such simulations. A model is typically a set of equations and a set of parameters for the equations that predict the current and charges at terminals of a device as a function of the voltages at the terminals. The model is fit to characteristics of a particular process in which some of the characteristics are represented by sample devices and some of the characteristics are different from available hardware. Such models are normally built while the process is still under development.
Current practice is to first fit a model to the available hardware, and then adjust the model to match target currents and/or threshold voltages at specific conditions while minimizing distortion of the model. This process is time consuming because it involves two model fittings and construction of a set of target currents which are self consistent is difficult. For example, each model fitting involves an optimization process in which the equations and/or parameters are iteratively adjusted to meet the hardware measurements (e.g., in a first model fitting) and the target values (e.g., in a second model fitting).
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.